The term “sludge” is a generic description of an oily waste stream that typically has a high solids content and varying quantities of hydrocarbons and water. Certain sludges, such as those generated in the production of various hydrocarbon products, includes vessel sludges, tank bottom sediments and emulsions from water treatment systems. Waste sludge resulting from producing oil and gas wells, for example, is often stored in open pits where it may be left for considerable time before being treated. During such aging periods, the sludge undergoes chemical changes including the effects of weathering and volatilization. It is desirable to treat the sludge to reduce the risk of contamination of the surrounding area and to recover the valuable hydrocarbon component in the sludge.
Traditionally, disk stack centrifuges have been used to condition slope oil or sludge, but they are only effective for non-emulsified water and oil blends. However, due to the existence of the in-situ natural emulsifiers, production sludges are characterized by strong water-in-oil emulsions. For such blends, a disk stack centrifuge is ineffective. It would be an improvement in the art to have a method and apparatus that thermally and chemically treats the sludge.